Encoder Apparatus with Frequency-Isolated Reference Mark Coils
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Solution Overview
Problem
Magnetic field interference between the reference mark and the scale in encoder apparatuses leads to measurement errors, particularly when using magnetic scales.
Innovation Solution
An encoder apparatus utilizing a reference mark with first and second scale coils and a head featuring transmitting and receiving coils to generate an origin signal through electromagnetic induction, isolating the magnetic fields by frequency, thereby reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic scale is used with a reference mark made of magnet or iron, then the origin signal can be generated, but magnetic field interference occurs between the reference mark and the scale leading to measurement errors
Solution Approach 1:
The patent introduces electromagnetic induction as an intermediary mechanism between the reference mark and the scale. Instead of direct magnetic field interaction, the system uses a magnetic sensor to detect magnetic field changes caused by electromagnetic induction from the scale, thereby mediating the interaction and reducing direct magnetic field interference between the reference mark and scale
Solution Approach 2:
The patent replaces the direct magnetic field interaction system with an electromagnetic induction-based detection system. The magnetic sensor detects position information through electromagnetic induction rather than direct magnetic field reading, substituting the harmful direct magnetic interaction with a less interfering electromagnetic induction mechanism
2Volume of moving object
If the reference mark and scale are positioned close to each other, then the apparatus size can be reduced, but magnetic field interference increases
Solution Approach 1:
The patent replaces direct magnetic field sensing with electromagnetic induction-based detection. This substitution allows the system to maintain compact dimensions while reducing magnetic field interference, as the electromagnetic induction mechanism is less sensitive to proximity-based interference than direct magnetic field reading
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces magnetic field interference, enhancing measurement accuracy and allowing for compact design while maintaining resistance to foreign substances and enabling commonality across different apparatus sizes.
Implementation Method 1
a transmitting coil configured to transmit an electromagnetic wave to the first scale coil in a non-contact manner
Implementation Method 2
a receiving coil configured to receive the electromagnetic wave from the second scale coil in a non-contact manner
Data Source
AI summary
Provided is an encoder device capable of reducing interference between a magnetic field generated in a reference mark and a magnetic field generated in a scale. An encoder device is provided with a reference mark and a head. The reference mark has: a first scale coil; and a second scale coil electrically connected to the first scale coil. The head has: a transmission coil that transmits an electromagnetic wave without any contact to the first scale coil; a reception coil that receives an electromagnetic wave without any contact from the second scale coil; and electric circuits that generate a pulse for generating an origin signal from the electromagnetic wave received by the reception coil, if the transmission coil faces the first scale coil and the reception coil faces the second scale coil.